Definitive Proof That the Simpson Children Have Aged

In Season 1, Episode 1 of The Simpsons, Bart (10) and Lisa (8) jump up from the sofa when they hear their father return home from work. "Daddy! Daddy! We're so glad to see you!" they shout, running from the cheek pinches of Aunts Patty and Selma and into Homer's arms. This is just one of the ways, throughout the episode, that Bart and Lisa act their age. Bart pulls off Santa's beard, Lisa sits on Grandpa's knee and (31-year-old spoiler alert) both react with unabashed glee at the arrival of the new family dog, Santa's Little Helper.

Like a desperate GCSE English student feeling the sweat pool at the back of their knees in the middle of a tepid exam hall, please: compare and contrast these scenes with the very latest episode of The Simpsons. In Season 31, Episode 17, Marge seeks the advice of Bart (10) and Lisa (8) when debating whether to take a job at a heavyweight boxer's cannabis dispensary. Lisa responds by telling Marge that cannabis is legal in their state, while Bart says, "It's basically the same thing as working in a liquor store," and, "Everyone's selling crap to stoners now." Which leads me, like another (much better) GCSE English student, to my thesis.

Though it is widely accepted that the Simpson family do not age, and the Simpson children remain perpetually 10, 8 and 1, this is a lie. Somewhere between the Golden Age of The Simpsons (Seasons 3-8) and today, the Simpson children grew up. Bart, Lisa and – Lord have mercy! – even Maggie are now adults.

Season 1, Episode 1 isn't the best evidence for this. Hardcore fans claim the show didn't hit its stride until Season 3, and it's true the characters weren't yet fully formed (who is early Ralph Wiggum, and is he single?). Yet thanks to the 30 seasons of the show now available on Disney+, it is easier than ever to watch the Simpsons children deteriorate into old age. Compare! Contrast! Despair!

Lisa Marie Simpson has always been hyper-intelligent, but in the early and best years of The Simpsons she remained advanced for her age. In one of the first truly great episodes, Season 1's "Moaning Lisa", the eight-year-old becomes depressed (and refuses to play dodgeball) because she is troubled by the meaning of existence. Yet despite her deep thoughts, she remains very much a child. She is Giddy Up-ped on Homer's knee. She dutifully listens to Marge’s advice that she should suppress her feelings and smile. Later, she powerfully laments in her first blues song: "I got a bratty brother / He bugs me every day / This morning my own mother / Gave my last cupcake away."

Despite her intelligence, early Lisa is a child who wants to impress her parents, not a know-it-all who looks down on them (with the notable exception of Season 2's iconic, "You, sir, are a baboon! Baboon, baboon, baboon, baboon!"). In a Season 3 episode that critics named me have called "an absolute belter", Lisa gambles with Homer because she wants to be closer to her dad. She is rewarded with a Malibu Stacy chinchilla coat, and it takes her a while to realise Homer is using her. She's smart, but she still has a lot to learn. When Bart says he's learned "the touch of death" in karate class, she believes him ("Hey quit it, Bart! Quit it! Quititquititquititquitit!"). She becomes the Lizard Queen because she drinks the dirty ride water at Duff Gardens.

Lisa was always politically engaged, but her political power was limited by her age. In Season 5’s iconique episode "Lisa vs. Malibu Stacy", Lisa struggles to get the attention of adults because, you know, she's eight. "It's awful being a kid. No one listens to you," she laments. By Season 9, Episode 8 – six episodes after the "The Principal and the Pauper", the episode many consider to mark the end of the Golden Age – Lisa both rocks up to a building site with her personal attorney and appears on Kent Brockman's Smartline when she is trying to convince the town a fossil she found isn't a dead angel. She calls the townspeople "morons", belittles Marge and declares, "You can either accept science and face reality… or you can believe in angels and live in a childish dreamworld." The Happy Little Elves may remain above Lisa's bed, but they are no longer in her heart.

It's ironic that the act of reducing a character to a single trait is called "Flanderization", when Lisa Simpson is the most Flanderized character in TV history. Lisa began ageing in Season 9 and never stopped. By Season 13, she successfully lies about being a college student – an entire lecture hall gasps when her secret is revealed – meaning she is now at least 16. By Season 22, she is intelligent enough to invent a brand new drug. According to a study by the National Bureau of Economic Research, 42 percent of innovations occur when creators are in their thirties, so 30 Lisa is.

In Season 29, a statue of Louis Armstrong comes to life and speaks with Lisa – clearly her mind has become addled in old age. Using these extremely flawless calculations, we can assume Lisa Simpson is now 60 years old.

The best Bart-centric episodes fundamentally star a little boy. Though his juvenile delinquencies have always been fairly adult (he gets a tattoo in the first ever episode), his heart and soul remained ten for many years. In possibly the best episode of The Simpsons ever, Season 7’s "Marge Be Not Proud", he steals a video game, is genuinely terrified by a security guard, buys his mum a sweet gift and pretends to like Lee Carvallo's Putting Challenge. But the saddest scenes in the episode are when Marge decides Bart is grown up – the family don't wait for him to make snowmen, he doesn’t get tucked into bed at night and his marshmallow inflates grotesquely when he attempts to make his own hot chocolate.

In Season 16, Bart loses his last baby tooth and decides he is now an adult. Like Lisa, Bart is no longer constrained by his age – after throwing away his toys, including his Krusty doll (please!) – he goes on to earn hundreds of dollars selling slogan T-shirts and becomes the man of the house. Bart continues to age at a steady rate – by Season 18, Episode 12 he is driving a car and has fallen in love with a teenage girl named Darcy, who he makes out with and nearly marries. Compare this to the first (and best) episode where Bart falls in love with a teen, Season 4, Episode 8's "New Kid on the Block", in which Bart refuses to wash his hand after Laura Powers spits in it.

In Bart's best Golden Age episodes, he was a boy embarrassed to love ballet, a boy booted in the butt in Australia for running up a large phone bill and a boy frightened after selling his soul. And in Season 2, Episode 7, after he destroys Lisa's Thanksgiving centrepiece, he is a boy who doesn't always understand himself. "Why did you burn my centrepiece? Come on. Because you hate me or because you’re bad?" Lisa asks. Emotionally, Bart replies: "I don’t know! I don’t know why I did it! I don’t know why I enjoyed it! And I don’t know why I’ll do it again!" You can’t show me a more realistic brother/sister relationship, because there isn’t one.

Bart began ageing earlier than Lisa, around Season 7. This was the time he stopped regularly making prank calls to Moe – by Season 30, he is pranking the bartender by ordering him a Russian bride from the dark web*. Slowly, Bart Simpson evolved from a prankster capable of feeling guilt and remorse to a hardened sociopath. In 1831, mathematician Adolphe Quetelet wrote a foundational criminology text in which he outlined the "age-crime curve", arguing an individual’s crimes increase steadily with age until their criminality peaks around age 25. As Bart Simpson has now stolen an entire wedding registry of gifts (Season 15), killed innocent cats by placing them, alongside sticks of dynamite, in his principal’s trousers (Season 18) and both murdered (and covered up the murder of) his classmate Martin Prince (Season 19, please don't watch it), we can only hope he has hit his peak.

Bart is now 25 years old.

*Though Bart does intermittently prank call Moe again, his trickery is crude and disturbed. In Season 22, for example, he asks the bartender for Tess T. Culls, an insult to the memory of Maya Buttreeks.

Alarming, disturbing, grim, gross, wrong – my reaction to the brand new short "Playdate with Destiny", which was screened in cinemas earlier this year before Pixar's Onward. In the short film, Maggie Simpson falls in love with a baby boy and "drowns her sorrows in baby formula" (citation: Wikipedia dot com). The whole thing is so depraved that it's only acceptable if Maggie is at least 21, so 21 she is.

@ameliargh